Abstract 745: Comparison of Fractional Flow Reserve of Composite Y-grafts With Saphenous Vein or Right Internal Thoracic Arteries
Introduction: Composite Y-grafts allow a more efficient use of graft conduits without the need to touch the ascending aorta, which can be essential in some patients with diseased aorta. Among other conduits, the saphenous vein graft (SVG) may be an alternative to the radial artery or to the right internal thoracic artery (ITA) in elderly patients. Theoretical inconvenients of composite grafts are their dependence on the flow capacity of the proximal left internal thoracic artery and the risk of an uneven distribution of flow in both branches.
Material and methods: We measured graft conductance of 17 composite Y-grafts made with the left ITA anastomosed to the LAD in all cases and with either the free right ITA (n=10) or a SVG (n=7) implanted proximally to the left ITA and distally to the LCX territory. During routine cardiac catheterisation performed 6 months after surgery, intra-graft pressures were measured using a 0.014-inch pressure-wire advanced distally in the left ITA main stem close to the proximal Y anastomoses (ITA-stem) and in the distal part of each branch at the site of their implantation to the LAD (ITA-LAD) or LCX (ITA-LCX or SVG-LCX) system. At each site, the pressure gradient between aorta and the graft was measured in basal conditions and during maximal hyperemia induced by intragraft bolus injection of 40μg of adenosine.
Results: At baseline, the pressure gradient was minimal between aorta and the ITA-stem (2±1 mmHg), the ITA-LAD (4±2 mmHg), the ITA-LCX (3±1 mmHg) and the SVG-LCX (2±2 mmHg). During hyperemia, the pressure gradient increased significantly (all p<0.001 versus baseline) to 6±2 mmHg in the ITA-stem, 9±4 mmHg in the ITA-LAD, 9±3 mmHg in the ITA-LCX and 7±4 mmHg in the SVG-LCX. Fractional flow reserve was 0.94 ±0.2 in ITA-stem, 0.90±0.04 mmHg in the ITA-LAD, 0.91±0.03 mmHg in the ITA-LCX and 0.92±0.06 mmHg in the SVG-LCX. No difference between the two types of composite Y-grafts was observed for pressure gradients or FFR measured in ITA-stem or in distal branches.
Conclusion: Composite Y-grafts with saphenous vein or right internal thoracic arteries allow similar and adequate reperfusion of the left system with minimal resistance to maximal flow and an even distribution of flow in both distal branches.